John Ruskin - The Elements of Drawing, in Three Letters to Beginners

26. In leading the color down, you will find your brush continually go over the edge of the square, or leave little gaps within it. Do not endeavor to retouch these, nor take much care about them; the great thing is to get the color to lie smoothly where it reaches, not in alternate blots and pale patches; try, therefore, to lead it over the square as fast as possible, with such attention to your limit as you are able to give. The use of the exercise is, indeed, to enable you finally to strike the color up to the limit with perfect accuracy; but the first thing is to get it even,—the power of rightly striking the edge comes only by time and practice: even the greatest artists rarely can do this quite perfectly.

27. When you have done one square, proceed to do another which does not communicate with it. When you have thus done all the alternate squares, as on a chess-board, turn the pasteboard upside down, begin again with the first, and put another coat over it, and so on over all the others. The use of turning the paper upside down is to neutralize the increase of darkness towards the bottom of the squares, which would otherwise take place from the ponding of the color.

28. Be resolved to use blotting-paper, or a piece of rag, instead of your lips, to dry the brush. The habit of doing so, once acquired, will save you from much partial poisoning. Take care, however, always to draw the brush from root to point, otherwise you will spoil it. You may even wipe it as you would a pen when you want it very dry, without doing harm, provided you do not crush it upwards. Get a good brush at first, and cherish it; it will serve you longer and better than many bad ones.

29. When you have done the squares all over again, do them a third time, always trying to keep your edges as neat as possible. When your color is exhausted, mix more in the same proportions, two teaspoonfuls to as much as you can grind with a drop; and when you have done the alternate squares three times over, as the paper will be getting very damp, and dry more slowly, begin on the white squares, and bring them up to the same tint in the same way. The amount of jagged dark line which then will mark the limits of the squares will be the exact measure of your unskillfulness.

30. As soon as you tire of squares draw circles (with compasses); and then draw straight lines irregularly across circles, and fill up the spaces so produced between the straight line and the circumference; and then draw any simple shapes of leaves, according to the exercise No. II., and fill up those, until you can lay on color quite evenly in any shape you want.

31. You will find in the course of this practice, as you cannot always put exactly the same quantity of water to the color, that the darker the color is, the more difficult it becomes to lay it on evenly. Therefore, when you have gained some definite degree of power, try to fill in the forms required with a full brush, and a dark tint, at once, instead of laying several coats one over another; always taking care that the tint, however dark, be quite liquid; and that, after being laid on, so much of it is absorbed as to prevent its forming a black line at the edge as it dries. A little experience will teach you how apt the color is to do this, and how to prevent it; not that it needs always to be prevented, for a great master in water-colors will sometimes draw a firm outline, when he wants one, simply by letting the color dry in this way at the edge.

32. When, however, you begin to cover complicated forms with the darker color, no rapidity will prevent the tint from drying irregularly as it is led on from part to part. You will then find the following method useful. Lay in the color very pale and liquid; so pale, indeed, that you can only just see where it is on the paper. Lead it up to all the outlines, and make it precise in form, keeping it thoroughly wet everywhere. Then, when it is all in shape, take the darker color, and lay some of it into the middle of the liquid color. It will spread gradually in a branchy kind of way, and you may now lead it up to the outlines already determined, and play it with the brush till it fills its place well; then let it dry, and it will be as flat and pure as a single dash, yet defining all the complicated forms accurately.

33. Having thus obtained the power of laying on a tolerably flat tint, you must try to lay on a gradated one. Prepare the color with three or four teaspoonfuls of water; then, when it is mixed, pour away about two-thirds of it, keeping a teaspoonful of pale color. Sloping your paper as before, draw two pencil lines all the way down, leaving a space between them of the width of a square on your chess-board. Begin at the top of your paper, between the lines; and having struck on the first brushful of color, and led it down a little, dip your brush deep in water, and mix up the color on the plate quickly with as much more water as the brush takes up at that one dip: then, with this paler color, lead the tint farther down. Dip in water again, mix the color again, and thus lead down the tint, always dipping in water once between each replenishing of the brush, and stirring the color on the plate well, but as quickly as you can. Go on until the color has become so pale that you cannot see it; then wash your brush thoroughly in water, and carry the wave down a little farther with that, and then absorb it with the dry brush, and leave it to dry.

34. If you get to the bottom of your paper before your color gets pale, you may either take longer paper, or begin, with the tint as it was when you left off, on another sheet; but be sure to exhaust it to pure whiteness at last. When all is quite dry, recommence at the top with another similar mixture of color, and go down in the same way. Then again, and then again, and so continually until the color at the top of the paper is as dark as your cake of Prussian blue, and passes down into pure white paper at the end of your column, with a perfectly smooth gradation from one into the other.

35. You will find at first that the paper gets mottled or wavy, instead of evenly gradated; this is because at some places you have taken up more water in your brush than at others, or not mixed it thoroughly on the plate, or led one tint too far before replenishing with the next. Practice only will enable you to do it well; the best artists cannot always get gradations of this kind quite to their minds; nor do they ever leave them on their pictures without after-touching.

36. As you get more power, and can strike the color more quickly down, you will be able to gradate in less compass; 9beginning with a small quantity of color, and adding a drop of water, instead of a brushful; with finer brushes, also, you may gradate to a less scale. But slight skill will enable you to test the relations of color to shade as far as is necessary for your immediate progress, which is to be done thus:—

37. Take cakes of lake, of gamboge, of sepia, of blue-black, of cobalt, and vermilion; and prepare gradated columns (exactly as you have done with the Prussian blue) of the lake and blue-black. 10Cut a narrow slip, all the way down, of each gradated color, and set the three slips side by side; fasten them down, and rule lines at equal distances across all the three, so as to divide them into fifty degrees, and number the degrees of each, from light to dark, 1, 2, 3, etc. If you have gradated them rightly, the darkest part either of the red or blue will be nearly equal in power to the darkest part of the blue-black, and any degree of the black slip will also, accurately enough for our purpose, balance in weight the degree similarly numbered in the red or the blue slip. Then, when you are drawing from objects of a crimson or blue color, if you can match their color by any compartment of the crimson or blue in your scales, the gray in the compartment of the gray scale marked with the same number is the gray which must represent that crimson or blue in your light and shade drawing.